Au(I)-complexes ligated by hybrid P,S,N-ligands as the efficient catalysts for hydration of phenylacetylene

Abstract

The incorporation of –PPh2 group in the parent molecule of 1-(thiazol-2′-yl)-imidazole afforded the hybrid P,S,N-ligands of 1 and 2 respectively. The former was quarternized by MeOTf to give the ionic hybrid P,S-ligand of 1′. The single crystal X-ray diffraction analyses of the corresponding mono-nuclear Au(I)-complexes of 1A and 2A indicate that the Au(I)-centered vectors in each are in a slightly distorted linear configuration, in which Au(I) center is diagonally coordinated by one Cl− and one phosphine without the coordinating interaction to N (or S)-donors. When the mono-nuclear Au(I)-complexes of 1A, 1′A, and 2A were employed as the catalysts for hydrations of phenylacetylene in aqueous-methanol media with the involvement of AgOTf and H2SO4, the reactions over 1A proceeded selectively according to Markovnikov's rule with much high yields of acetophenone than those over 1′A and 2A, indicating that the available additional S-, and N-donors in 1A with less steric hindrance synergetically protected the active Au(I)-complex species against deactivation during the catalytic cycle.